1. Field of the Invention
The present invention relates to an automatic analyzer for the qualitative and quantitative analysis of body fluids including serum and urine and, more particularly, to an automatic analyzer provided with a B/F separation mechanism (bound/free separation mechanism) for magnetically separating components idiosyncratically bonded to markers.
2. Description of the Related Art
Immunity measurement is the qualitative and quantitative determination of a specified antigen or antibody contained in a biological specimen, such as blood, urine or saliva. Usually, immunity measurement uses an antigen or an antibody suitable for measuring a measuring object and bonded to solid particles. The measuring object contained in the specimen is brought into contact with the antigen or antibody. Then, the measuring object labeled by an enzyme, namely, a labeled compound, is made to react with the antigen or antibody peculiarly reactive with the measuring object to bind the measuring object, and then the specimen is rinsed repeatedly to remove the unreacted enzyme-labeled antigen, namely, free antigen for bound/free separation (hereinafter, referred to as “B/F separation). Then, the labeled matter bonded to the measuring object of the specimen is measured to determine the quantity of the measuring object contained in the specimen.
Thus, immunity measurement requires troublesome operations for distribution, dilution, stirring, B/F separation and moving solid particles. Usually, the solid particles are polystyrene beads, magnetic particles or parts of the wall of a reaction vessel. Techniques and automatic analyzers using magnetic particles as solid particles for magnetic B/F separation have been developed, for example, an automatic analyzer proposed in, for example, JP-A-1996-043400 (Patent Document 1) is provided with a B/F separation mechanism.
The automatic analyzer proposed in JP-A-1996-043400 (Patent Document 1) uses magnetic particles as the solid particles to which a labeled substance is bonded, contains a liquid containing the labeled substance bonded to the magnetic particles in plural reaction vessels, and magnetically separates the solid particles from the liquid phase while the plural reaction vessels are moved on a processing line. Plural magnets are arranged along the processing line and apply a magnetic field to the liquid to move the reaction vessels at an increased moving speed.
[Patent Document 1] JP-A-1996-043400 [Patent Document 2] Japanese Translation of Unexamined PCT Application No. 1994-505673
B/F separation is used mainly by an automatic immunity analyzer. Therefore, BF separation is required to achieve high-speed separation and capturing at high capturing efficiency from the viewpoint of rapid measurement and multiple-specimen processing. Since a limited space is available for installing the automatic analyzer in the examination room, the automatic analyzer is required to be capable of being installed in a small space.
When external force, such as centrifugal force, inertial force or magnetic force, is used, for capturing the solid particles for B/F separation, there is a limit to the capturing efficiency. Capturing efficiency is a value obtained by dividing the number of the solid particles captured by B/F separation by the number of the solid particles contained in the solution before B/F separation and the separating time for which B/F separation is continued. The higher the capturing efficiency, the greater the number of the captured solid particles captured in a shorter time.
When a turntable and magnetic force are used for B/F separation as mentioned in JP-A 1996-043400 (Patent Document 1), magnets can be placed only on the outer side surface and the inside surface.